JP2001074226A - Heating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating furnace, which can surely exhaust harmless gas by heating harmful gas generated from an incinerator and the like and which is high in heating/decomposition efficiency. SOLUTION: This heating furnace 1 comprises a furnace body of a heat- resistant material having an inlet 2 and an outlet 3 of a channel, and a heating element 5 filled therein from the side of the inlet 2 to that of the outlet 3. The fluid flowing into the furnace body can be heated to at least 1300 deg.C or more by energizing this heating element 5, and the interior of the furnace and the outlet 3 are enlarged in diameter than the inlet 2 of the channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace, and more particularly, to a heating furnace capable of heating an exhaust gas or the like generated from an incinerator or the like to discharge a harmless gas.

[0002]

2. Description of the Related Art To date, harmful gases generated from incinerators and the like are generally sent to a large-scale secondary combustion furnace through a dust removal device that is an exhaust gas treatment facility, a wet dust scrubber, and the like. It is released in a way that it is decomposed by heating and detoxified by a burner made of ash.

[0003] However, since the method of thermally decomposing and releasing harmful substances in this way is a combustion method using petroleum as a fuel, NOx, SOx and the like generated from the fuel itself cannot be removed. It cannot always be discharged as clean air.

[0004]

Therefore, as a combustion system utilizing clean energy, an electric heating system using an electric heater has been considered. However, since it is an indirect heating system, a large amount of power is consumed. The efficiency of heating and decomposing harmful exhaust gas is low, and it is not always possible to make it harmless and discharge it.

Accordingly, an object of the present invention is to provide a method of heating a harmful exhaust gas generated from an incinerator or the like to reliably discharge a harmless gas in view of the above-mentioned problems of the related art.
Yet another object of the present invention is to provide a heating furnace having high heating and decomposition efficiency.

[0006]

The above object is achieved by the invention described in each claim. That is, the characteristic configuration of the heating furnace according to the present invention is a furnace body having a flow path inlet and an outlet and formed from a heat-resistant material, and the inside of the furnace body is filled from the flow path inlet side to the outlet side. A heating element, and by supplying a current to the heating element, the fluid flowing into the furnace body can be heated to at least 1300 ° C. or more by the heating element, and the inside and the outlet of the furnace body can be heated. Is enlarged from the flow channel inlet.

According to this configuration, since no petroleum is used to thermally decompose the exhaust gas, no harmful gas is generated from the fuel, and the furnace is heated to a high temperature of 1300 ° C. or more. Therefore, NOx, SOx, HC in exhaust gas
Not only L, HCN and other harmful gases but also dioxins are surely decomposed and made harmless, so that the gas released from the heating furnace of the present invention can be extremely purified. Moreover, since the diameter of the inside of the furnace body and the outlet of the flow passage are larger than that of the inlet of the flow passage, the exhaust gas introduced into the furnace is decelerated in the furnace, and the residence time in the furnace can be secured. Decomposition of the exhaust gas is ensured. Also, by forming a connecting means such as a flange at the end of the flow channel, it can be easily connected to the exhaust gas discharge points of existing various furnaces. The heating furnace of the present invention can be used effectively.

It is more preferable that the inside of the furnace is heated to 1350 ° C. or higher. This is because the decomposition of the harmful gas is accelerated, the processing speed can be improved, and the detoxification can be more reliably promoted.

A large number of the heating elements are arranged in a multilayer structure inside the furnace from the flow path inlet side to the outlet side, and the fluid is discharged to the outlet side while contacting the heating elements. Is preferred.

According to this structure, the exhaust gas introduced into the furnace is decelerated by the heating elements arranged in layers inside the furnace body, and a turbulent flow is formed, so that the residence time in the furnace is reduced. It is longer, which is advantageous because heating and decomposition are accelerated.

It is preferable that a deceleration means for decelerating the flow velocity of the fluid is arranged between the heating elements arranged in a layered manner.

According to this configuration, the exhaust gas introduced into the furnace is greatly decelerated by the action of the speed reducing means, for example, the baffle plate, in addition to the presence of the heating element, and a turbulent flow is formed. The contact time is prolonged, and the residence time in the furnace is further prolonged, so that heating and decomposition are accelerated, which is convenient.

However, depending on the density of the heating element or the speed reduction means, an exhaust pump may be attached downstream of the flow path outlet to smoothly promote the flow of the exhaust gas in the furnace.

It is preferable that the heating element is made of tungsten which has been subjected to an antioxidant treatment and has a fluid passage formed therein.

According to this structure, since tungsten has sufficient heat resistance, it generates heat when energized and easily achieves a furnace temperature of 1300 ° C. or more.
The introduction of a large amount of exhaust gas is convenient because it functions as a durable heating element. Tungsten may be in a plate shape or a rod shape, or may be a plate shape obtained by weaving linear tungsten into a flat shape and having air permeability. As an antioxidant treatment for tungsten, it is possible to coat heat-resistant ceramic fine particles on the tungsten surface.

It is preferable that the heating element is a Kanthal heating element.

According to this configuration, the Kanthal heating element can easily heat the inside of the furnace to a temperature of 1300 ° C. or more, so that it functions as a durable heating element even when a large amount of exhaust gas is introduced. The Kanthal heating element may be a rod-shaped, linear, or plate-shaped heating element, or a bar-shaped or linear Kanthal heating element may be arranged in a multilayer. When the Kanthal heating element is arranged horizontally in the furnace, it is preferable to support the Kanthal heating element on a support. This is because when the Kanthal heating element reaches a higher temperature than expected, it is possible to reliably prevent the Kanthal heating element from being deformed, which is convenient.

It is preferable to generate electric power by supplying waste heat discharged from the outlet of the flow path to a power generating device, and to use the obtained electric power for heat generation of the heat generating element.

According to this configuration, since the purified air discharged from the flow path outlet of the furnace body has a considerably high temperature, this high-temperature air is supplied to a power generator outside the furnace to generate power. By using the electric power for heating the heating element, energy costs can be reduced. In such a case, as a power generation device, a turbine-driven power generation device that uses high-temperature steam to generate heat by exchanging heat with high-temperature air discharged outside the furnace may be used, and waste heat may be used. Used directly for heating the cylinder, the piston is reciprocated by repeating the expansion and discharge of air in the cylinder, and the power is converted into rotational motion and taken out. You may do so.

[0020]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic longitudinal sectional structure of a heating furnace according to the present embodiment, and FIG. 2 shows a sectional structure taken along line II-II of FIG. In the heating furnace 1, exhaust gas that has passed through a dust removal device such as a cyclone or directly introduced from an incinerator or the like is supplied through a flow path composed of pipes or the like. It has a passage entrance 2 and a passage exit 3 which is enlarged in diameter. The heating furnace 1 has an outer shell (not shown) made of a steel shell, is provided with a heat-insulating refractory material on the inner wall, and has a substantially conical inlet portion 1b and a centrally located furnace body having a cylindrical structure. Part 1a and a substantially conical outlet part 1
c, and each part is combined at the time of assembly,
It is designed to be integrally joined so that it can be disassembled. Various existing connection methods, such as tightening and fitting the bolts 9 at the flange portion, and further covering the reinforcing material from the outer wall, can be adopted for connection of the respective portions. Depending on the amount of gas to be processed sent into the furnace, it is necessary to increase the capacity of the furnace body,
In this case, the heating furnace having the required capacity can be modified by connecting a plurality of central portions 1b so as to have the required capacity.

The inside of the heating furnace 1 is provided with a large number of heating elements 5 filled from the inlet side to the outlet side of the flow path, and the fluid flowing into the inside is heated by the heating elements 5 by at least one.
It can be heated to 300 ° C or higher. The heating element 5 has a disk shape extending across the furnace walls facing each other, and is formed so that a large number of pores 5a serving as fluid passages penetrate in the thickness direction. Below the heating element 5, a support 6 made of heat-resistant and porous plate-shaped ceramic is provided.
Is arranged. Although not necessarily required, the support 6 functions as a speed reducing means for reducing the flow rate of the exhaust gas, and when the heating element 5 is made of metal, the high-temperature strength decreases when exposed to a high temperature for a long time. This is convenient because it is possible to surely prevent the possibility of occurrence. Needless to say, baffles having various shapes as deceleration means may be arranged at appropriate places in the furnace separately from the support 6.

An external power supply (not shown) is connected to these heating elements 5.
Electric power is supplied to generate heat. Naturally, the supplied power is supplied in conjunction with the temperature control based on the measurement result of the furnace temperature measured by a thermocouple described later.

The flow path inlet 2 is connectable to an upstream pipe for supplying exhaust gas, etc., and is provided with a shutter device 4 which is remotely operated from a control device (not shown) or manually operated. It can be opened and closed freely. A similar shutter device 7 is also provided at the flow path outlet 3,
Similarly, it can be opened and closed manually or remotely by a control device or the like. By appropriately controlling these two shutter devices 5, 7, the actual operation can be stably and efficiently maintained. In FIG. 1, reference numeral 8 denotes a thermocouple for measuring the temperature in the furnace, and a plurality of thermocouples are usually arranged in the furnace. The measurement result is sent to the thermometer,
The temperature inside the furnace is displayed and transmitted to a control device (not shown), and is used to control the inside of the furnace to a predetermined temperature. In that case, it is preferable to divide the heating element into several blocks from the furnace body inlet side to the outlet side, and to control the power supplied to the heating body in each block according to the temperature measurement result in each block. Reference numeral 10 denotes a conductor for supplying power to the heating element 5 from an external power supply (not shown).

The heating elements 5 are provided with a large number of through-holes 5a of several mm to several cm, and are arranged in multiple layers from the inlet side to the outlet side of the flow path. These heating elements 5 are arranged at appropriate intervals of about several mm to several tens cm, and the through holes 5 between adjacent heating elements 5 are arranged.
a is preferably arranged so as to be slightly shifted so as not to overlap from the furnace body inlet toward the outlet, and in this case, the exhaust gas flowing through the furnace is frequently generated with the surface of the heating element 5. It can be conveniently brought into contact.

[Another Embodiment] (a) In the above embodiment, a tungsten plate is used as a heating element. Instead, a tungsten wire may be densely woven in a mesh shape to form a flat plate. If a large number of the plate-like tungsten heating elements thus formed are superposed in the flow direction of the exhaust gas, the mesh size becomes finer, the residence time of the exhaust gas in the furnace can be lengthened, and the surface area in contact with the exhaust gas increases. can do. Also in this case, the surface of each tungsten wire is coated with a ceramic coating for preventing oxidation.

(B) In the above embodiment, a tungsten plate was used as the heating element. Instead, a Kanthal high-temperature heating element (trade name), which is a rod-shaped or linear Fe-Cr-Al-based alloy, MoSi ₂ May be used as a main component. in this case,
As shown in FIG. 3, a multi-stage shank-shaped heating element 15 is horizontally arranged so as to traverse the inside of the furnace, and a large number of through holes 16a are formed below the heating element 15 like a punching metal. A heat-resistant support 16 is provided.
In this way, when the inside of the furnace is heated to a high temperature, the heating element 15
Can be reliably prevented from being deformed, and the inside of the furnace can always be heated uniformly, which is convenient. The heating element 15 shown in FIG.
The heating elements 15 are arranged in a multi-layered manner inside the furnace body, and are decomposed by heating while contacting the heating elements 15 while passing through the inside of the furnace.

The support 16 may be made of ceramic or heat-resistant metal, and may have a shape other than a plate-like shape, such as a net-like shape in which many wires are densely knitted. In short, it is only necessary to maintain a certain level of strength and to have air permeability. Even with such a configuration, an atmosphere of 1300 ° C. or higher can be achieved inside the furnace, and the exhaust gas is reliably heated and decomposed to render it harmless.

Further, the heating furnace may be of a horizontal type, and a large number of Kanthal heating elements may be suspended from the ceiling in the furnace, and the exhaust gas may pass between them. In that case, the support 16 described above is not always necessary.

(C) Since the purified air discharged from the flow passage outlet 3 has a considerably high temperature, the high-temperature air is supplied to a power generator (not shown) to generate power.
By utilizing the electric power for heating the heating element,
Energy costs can be reduced. In such a case, a turbine-driven power generator that uses high-temperature steam as a power source by exchanging heat with high-temperature air discharged outside the furnace may be used as the power generator. Further, it is preferable to drive and generate electric power by driving the external combustion engine described below, because the efficiency can be increased.

That is, the waste heat released outside the furnace is directly used for heating the cylinder containing the piston, and the piston is reciprocated by repeatedly expanding and discharging the air in the cylinder, and the power is rotated. To drive and generate electricity. In this case, since the waste heat can be directly used for driving the cylinder, the efficiency is accordingly increased, which is convenient.

(D) The internal shape of the heating furnace is not limited to the structure shown in FIGS. 1 and 2, but various structures can be employed. For example, the furnace internal structure may be made spiral, and the residence time in the furnace may be lengthened while turning the exhaust gas. In the above embodiment, the example in which the heating furnace is vertical is shown, but the heating furnace may be horizontal, and the cross-sectional structure inside the furnace body is not limited to a cylindrical shape, but may be a square shape or another shape.

(E) The present invention can be applied not only to the treatment of exhaust gas generated from a large incinerator, but also to the treatment of exhaust gas from a small incinerator not provided with a dust removing device or the like. That is, since the heating furnace of the present invention can be easily connected to the chimney of an existing small incinerator, various harmful gases including dioxin and the like discharged through the chimney can be reliably prevented from being released to the atmosphere. It can also be used to treat exhaust gas from many small incinerators nationwide.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a heating furnace according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view similar to FIG. 2 of a heating furnace according to another embodiment.

[Explanation of symbols]

 2 Channel inlet 3 Channel outlet 5,15 Heating element 5a Fluid passage 6,16 Support

Claims (6)

[Claims] 1. A furnace body having a flow path inlet and an outlet and formed from a heat-resistant material, and a heating element filled inside the furnace body from the flow path inlet side to the outlet side. By energizing the heating element, the fluid flowing into the furnace body can be heated to at least 1300 ° C. or more by the heating element, and the inside of the furnace body and the outlet are enlarged in diameter from the flow path inlet. Heating furnace. 2. The heating element is arranged in a multilayer structure inside the furnace from the flow channel inlet side to the outlet side, and
The heating furnace according to claim 1, wherein the fluid is discharged to an outlet side while being in contact with the heating elements. 3. The heating furnace according to claim 1, wherein a speed reduction means for reducing the flow velocity of the fluid is provided between the heating elements arranged in a layered manner. 4. The heating furnace according to claim 1, wherein said heating element is made of tungsten which has been subjected to antioxidation treatment, and has a fluid passage formed therein. 5. The heating furnace according to claim 1, wherein said heating element is a Kanthal heating element. 6. The power generator according to claim 1, wherein power is generated by supplying waste heat discharged from the outlet of the flow passage to a power generator, and the obtained power is used for heat generation of the heating element. heating furnace.